1. Field of the Invention
This invention relates to a particular terpolymer produced by free-radical polymerization and its use for the separation of tall-oil soap from liquors resulting from the pulping of wood, especially that of trees readily commercially available and rich in resins and oil, such as Douglas fir and pine.
2. Description of the Prior Art
It is known that in the kraft or sulfate pulping process, tall oil can be recovered as a major by-product. Particularly in the pulping of pine or Douglas fir, tall oil, in the form of its sodium salt, is present in the relief liquors which are drawn from the digester. From these relief liquors, also called black liquor, some water is evaporated, and then the liquor is transferred to a skimming tank. The tall-oil soap tends to rise to the surface, and it can be readily skimmed off. A certain amount of tall-oil soap can be recovered in that way without further effort. Additional tall-oil soap remains in the black liquor, and this invention is concerned with how recovery of the remaining tall-oil soap can be achieved.